Differential pressure sensors have many applications in the oil and gas industry, in particular for the measurement of differential pressures in fluids produced from a well or in fluids that are to be injected into a well. Examples of such applications include a flow meter in which differential pressure is measured across a constriction, valves, such as choke valves in which a differential pressure is measured across the valve, or filters, wherein a differential pressure can be measured across the filter, for example to detect clogging or the like.
A differential pressure sensor generally has a first pressure inlet via which a first pressure to be measured is transmitted and a second pressure inlet via which a second pressure to be measured is transmitted. The differential pressure sensor then produces a signal that corresponds to the pressure difference between the first pressure and the second pressure. The pressure in the process fluid which is to be measured is generally transmitted via an intermediate working fluid (also termed fill fluid) to a sensor element. For transmitting the pressure from the pressure inlet to the intermediate working fluid, a membrane (e.g. isolating diaphragm) which separates the process fluid from the working fluid can be used. This way, it can be ensured that the working fluid has predefined properties and stays clear of contaminations.
A chamber may be formed around the membrane (isolating diaphragm) by mounting a cover to a housing of the differential pressure sensor. A problem is that the pressures to be measured are relatively high, so that a high force is applied to such cover from within the chamber, which pushes the cover away from the housing. Conventional mounting methods are not capable of achieving mounting forces that are able to withstand the pressure applied from within the pressure chamber. Providing additional mechanical support, for example by clamping, requires additional mounting steps and considerably slows down the assembly of such differential pressure sensor. Furthermore, such measures generally require a recalibration of the differential pressure sensor, since such additional clamping generally applies non-uniform forces to the covers, which is detected by the differential pressure sensor. Also, such configurations are relatively bulky, leading to an increased overall size of the differential pressure sensor.
It is thus desirable to provide a differential pressure sensor which is able to measure differential pressures at high absolute pressures, i.e. as a high pressure rating. Furthermore, it is desirable that such differential pressure sensor is relatively fast and simple to assemble and is relatively compact.